Time-delay relay



Oct. 10, 1950 J. 5. BAKER 2,525,334

TIIIE DELAY RELAY Filed Feb. 27, 1946 &

IN V EN TOR.

71% J. M 3/426, W2 #21144, 4 711 Patented a. 10, 1950 TIME -DELAY RELAYJohn S. Baken-Chicaio, 111., minor to Cook Electric Company, Chicago,Ill., a corporation of Illinois A plication February 27, 1946, SerialNo. 650,599

This application relates to time delay relays and more particularly totime delay relays wherein the time delay is produced by thermallyresponsive means.

Time delay relays usually include a relay embodying a coil, an armatureadapted to be attracted by the coil, and contacts arranged to beoperated by the armature along with some mechanism or apparatuseitherelectrical or mechanical to produce a delay in the functioning ofthe relay whether it is opening the contacts or closing them. Time delayrelays operating upon purely electrical principles usually are providedwith a short-circuited winding or slug in the relay magneticcircuit,'thereby providing a delay in the increase or decrease of therelay magnetic field, and hence, in the time of operation of thecontacts whether opening or closing. Time delay relays operating uponmechanical principles include dash pot devices or escapement mechanismsto delay operation of the relay armature after energization orde-energi'zation has occurred. Such prior expedients have not beencompletely satisfactory. Only relatively short time delay intervals areobtainable or the additional time delay apparatus combined with therelay renders the relay bulky and subject to mechanical failures. It isan object of the invention to provide an improved time delay relay inwhich the time delay is produced by thermally responsive means.

It is a further object or the invention to provide an improved timedelay relay that is not affected by ambient temperature variations.

It is a further object of the invention to provide an improved thermallyresponsive time tie- Claims. (Cl. 175-320) I ated by the armature.

lay relay: that is compact in form and simple in design.

In carrying out the invention in, one form, a time delay relaycomprising a coil, contacts adapted to be operated thereby, and athermally responsive element associated with the contacts forcontrolling the, operation ofthe coil after a time delay, is provided.In another form of the invention, a time delay relay is provided whichcomprises a coil, contacts adapted to be operated thereby, an energizingcircuit for the coil including a normally open pair of the contacts,another energizing circuit for the coil including normally openthermally responsive contacts, along with an electric heater intimatelyassociated with the thermally responsive contacts for controllingclosure thereof to energize the coil through the other circuit after atime 'delay,

the heel I5 and lying alongside coil I2.

end of plate I8 opposite to heel I5, the armature thereby to close thenormally open pair of contacts to complete the first energizing circuit.

For a more complete understanding of the in-' vention reference shouldnow' be had to the accompanying drawing in which:

Figure 1 is a side elevational view of a relay embodying the invention;

F Fig. 2 is a top plan view of the relay shown in ig. l;

Fig. 3 is an end elevational view of the relay shown in Fig. l;

Fig. 4 is a circuit diagram embodying the relay of Fig. 1 in schematicform;

Fig. 5 is a circuit diagram of another form of the invention;

Fig. 6 is a circuit diagram of a still further form of theinvention; and

Fig. '7 is a circuit diagram of still another form of the invention.

Referring more particularly to the drawing, the invention is shownembodied in a relay I0, including a frame II, a coil I2, an armature I3,and a series of contacts I4 adapted to be oper- The frame II has an'angularly bent portion or heel I5 to which the coil I2 including aniron core I6 is attached by means of a screw II. The frame II is alsoprovided with a plate I8 extending at right angles to At. the

are provided respectively upwardly and inwardly directed tongues 23 and24, which tongues rest uponthe top surface of plate I8 in theunenergized condition of coil I2.

Thecontact series I4 comprises two groups 3 springs 26 and 21 also havearc-resistant contacts at one end which are normally open. When thearmature I3 is attracted by coil I2, the contacts of contact springs 28and 23 are opened and the contacts of contact springs 26 and 21 areclosed, since the tongue 24 bears against an insulating nipple 32' whichis attached to contact spring 28, and the contact spring 21 is providedwith an insulating nipple 33 which is engaged by the contact spring 28.Thus, when the armature is pivoted around shaft I3, the tongue 24 movesthe contact oi. contact spring 28 away from the contact of contactspring 28 and correspondingly the contact of contact spring 21 is movedinto contact with the contact of contact spring 26. The second group ofcontacts includes the contact springs 32, 33, 34, 35 and 36 separatedfrom each other by means of insulators 31. The contact springs 32, 33,35 and 36 are provided with arc-resistant contacts at one end andreferring to Figs. 1 and 3, it will be seen that the contact spring 34includes a pair of contacts at its forward end, one of which is innormally closed relationship with the contact of contact spring 35, andthe other of which is in normally open relationship with the contact ofcontact spring 36. Thus when the armature I3 is actuated, the tongue 23,acting through an insulating nipple 20 attached to contact spring 36,moves the contact spring 36 into contact with one of the contacts ofcontact spring 34 to form a closed circuit, and at the same time itforces contact spring 34 away from contact spring 35 to form an opencircuit between the contacts of these two contact springs.

The contact springs 32 and 33 are thermally responsive elements such forexample as bimetallic strips and are so disposed with respect to eachother that if the two strips are heated equally they will be distortedor' bent in the same direction and thereby always maintain theircontacts in the same position, this position being normally open inFig. 1. Thus changes in ambient temperature, for example, will notchange the relative position of thermal elements 32 and 33. The thermalelement 33 is provided with an electric heater 38 which for example maybe an electric resistance wire wrapped around this element and insulatedfrom the surroundings by any suitable means, such for example as acoating of shellac or varnish. Referring to Fig. 4 and to Fig. l, theend of thermally responsive strip 32, opposite to the contact end, isconnected by means of a conductor 33 to one terminal of coil I2 and bymeans of conductor 59 to the corresponding end of the contact spring 36.Contact spring 34 issimilarly connected by means of conductors 4i and 58to the corresponding end of thermally responsive strip 33. One end ofelectric heater 38 is connected to contact spring 35, and the other endof the heater is connected through a conductor 42 and a variable contact43 to a resistor 44 and thence through a conductor 45 to one terminal ofcoil i2.

For an explanation of the operation of the invention reference isdirected to Fig. 4. A source of voltage, which for example may be abattery 41, is provided along with a switch 48, both connected incircuit with the relay for obtaining relay operation. While the battery41, a direct current source, has been shown, it will be understood thatother sources of power such for example as alternating current may beused. The circuit shown in Fig. 4 embodies the relay as shown in Fig. 1and is an arrangement whereacres.

4 by relay coil I2 is energized to operate the relay contacts a certaintime interval after switch 43 is closed. Thus the various elements areshownin their normally inoperative positions. On closing switch 48 acircuit is completed through heater 33 as follows: From battery 41through conductors 43 and 43, a portion of resistor 44. variable contact43, conductor 42, heater 38, conductor 53, contact spring 35, contactspring 34, conductor 4I, conductor 55 through switch 48. and conductor56 to the battery 41. Accordingly, the heater 33 begins to heat thethermally responsive element 33, which, after the incident time delayinterval, is distorted to close contact with thermally responsiveelement 32. At this occurrence a circuit is completed for energizingcoll I2 as follows: From battery 41 through conductor 43, through coilI2, conductor 33, thermal element 32, thermal element 33, conductor 58,conductor 55, switch 43, and conductor 56 to the battery 41.Accordingly, the coil I2 is energized, attracts the armature I3, andcloses the circuit between the contacts of contact springs 34 and 36 andopening at the same time the circuit between the contacts of contactsprings 34 and 35. Closing the circuit including the contacts of contactsprings 34 and 36 completes a second circuitfor energizing coil l2 asfollows: From battery 41 through conductor 43, coil I2, conductor 53,contact springs 36 and 34, conductors 4i and 55, switch 48, conductor 56to battery 41. Opening 'the circuit between the contacts of contactsprings 34 and 35 interrupts the circuit to heater 38 which accordinglyallows thermally responsive element 33 to cool, and hence, opens thecontacts between thermal elements 32 and 33. Opening the circuit betweenthese latter two elements interrupts the first energizing circuit forcoil I2 and the circuit is in position for repeat operation whenevertheswitch 48 is opened. Of course when armature I3 is attracted, thecircuits operated by contact springs 28 and 23 are opened and thecircuits operated by contact springs 26 and 21 are closed and vice versawhen the armature is released.

After switch 48 is closed, coil I2 is energized when thermallyresponsive elements 32 and 33 close the circuit between them and theselatter elements close the circuit whenever sufl'icient heat is producedby heater 33 to distort the element 33 suiiiciently to close thecontacts. Thus the time of energizing coil I2 is controlled by thethermally responsive elements 32 and 33 and the associated heater 38.Since resistor 44 may have varying portions thereof connected in circuitwith heater 38 by the variable contact 43, the amount of currentreceived by heater 38 may of course be controlled, and hence the timeelapsed before thermally responsive element 33 closes its contacts withthe corresponding element 32 may be controlled.

Fig. 5 illustrates schematically an embodiment of the invention in whichthe coil I2 of the relay is de-energized after an elapsed time intervalfrom the closing of switch 48. The coil I2 and the contact springs 26,21, Y28 and 23 correspond to the elements similarly numbered in Fig. 4.Associated with contact springs 26-23 in a manner similar to thatillustrated in connection with Figs. 1 and 4 are the contact springs 6|and 62, and thermally responsive elements 63 and '64, a resistanceheater 65 being intimately associated with thermally responsive element64 and connected thereto at one end as shown. In the inoperativeposition of this circuit, the thermally ruponsive elements 66 and 64 arein the closed position, and, when the heater 65 is energized, thethermally responsive element 64 after the incident time delay opens thecontacts between these elements. The contact springs 6| and 62 includingarc-resistant contacts form a normally open circuit.

When switch 46 is closed, an energizing circuit for coil I2 is completedas follows: From the battery 41 through conductor 66, through switch 46,conductor 61, coil |2 to battery 41. Coil |2 immediately attractsarmature l3, closes the contacts 01 contact springs 6| and 62 as well asthe contacts of contact springs 26 and 21, and opens the circuit betweenthe contacts of contact springs 26 and 26. When contact springs 6| and62 close the circuit between them, substantially no current is suppliedtherethrough to the thermally responsive elements 63 and 64 and the re-vlated elements since switch 48 effectively provides a short circuit.However, when the switch 46 is opened (the time delay of contactoperation occurs in this circuit after the switch is opened), a circuitis completed through the heater 65 as follows: From battery 41 throughconductor 66, conductor 16, conductor 66, heater 65, thermallyresponsive elements 64 and 63, closed contacts of contact springs 62 and6|, conductor 61, coil |2, and battery 41. Accordingly the heater 65begins to heat up and after the incident time interval the thermalelement 64 opens its contacts with thermal element 63, therebyde-energizing coil 2 which allows the armature to drop out and thevarious contacts to assume their normally inoperative positions. In thiscircuit, the heater for supplying heat to the thermally responsiveelements is unenergized when the switch 46 is closed and becomesenergized only when the switch 48 is opened. Thereafter, the coil I2 isde-energized when the thermally responsive elements open their contacts.

' In order to vary the time interval elapsing between opening of switch46 and opening of contacts 63 and 64, the variable resistor 66 isconnected to the thermally responsive element 64 and to the heater 65and through the variable contact 1| to the Junction of the conductors 16and 66. Thus the heater 65 is in one branch of a parallel circuit and aportion of the resistor 66 is in the other branch, the parallel circuitbeing in series with coil |2. Varying the value of the resistor 66 thenvaries the amount of current flowing through the heater 65 as is wellunderstood and hence, varies the time delay before de-energization ofcoil l2.

Fig. 6 illustrates an arrangement similar to Fig. 5 for producing a timedelay between the opening of switch 46 and the de-energization of coilI2. In this arrangement, the resistor 66 for varying the time delay ofheater 65 is connected directly in parallel with coil 2 rather than inone branch of a parallel circuit of which the heater 65 is in the otherbranch. In Fig. 6, when switch 48 is closed, current is supplied to coill2 through a circuit including battery 41, conv and conductors 14 and 15to 41, conductor 16, conductor 66, heater 66, thermal elements 64 and63, closed contacts 01' contact springs 62 and 6|, conductors 12 and 16,coil |2, battery 41. Thus the heater 65 supplies heat to element 64which opens its contact with element 66 after the incident time delay tode-energize coil |2. Placing the resistance 66 in parallel to coil |2places a parallel circuit combination including resistor 66 and coil 2in series with heater 65 whenever switch 46 is opened. Hence by varyingthe value of resistor 66, the value of the parallel resistancecombination oi resistor 66 and coil I2 is varied, and hence the totalcurrent taken by heater 65 is varied. This varies the heating value ofheater 65, and hence the time delay pro- ;igced by thermally responsiveelements 64 and The circuit of Fig. 7 combines the circuits of Fig. 4and Fig. 5. Thus the conductors and 56 of Fig. 4 and the conductor 16and the contact spring 6| of Fig. 5 are connected across the switch-46.In the normally inoperative position of the circuit (switch 48 is open),the contacts of contact springs 6| and 62 are open, the contacts ofcontact springs 34 and 35 are closed, and the contacts of contactsprings 34 and 36 are open. When switch 46 is closed a circuit iscompleted through heater 38, through the circuit previously described inconnection with Fig. 4, and since the contacts of contact springs 6| and62 are open no energy is supplied to heater 65. After thermal element 33is heated sufliciently by heater .36, the thermalelements 33 and 32close to energize coil |2, also through a circuit previously described,the coil becoming energized and closing contacts of contact springs 34and 36 while at the same time opening the contacts of contact springs 34and 35. Opening the circuit of contact springs 34 and 35 de-energizesheater 36. permitting it to cool for a repeat operation. When coil |2picks up the contact springs 26 and 21 are closed and the contactsprings 21 and 26 are opened. Thus the circuit described produces adelay in the energization of coil |2 after closing of switch 48, theamount of the delay being determined by the setting of variable contact43 on resistor 44.

ductor 10, switch 48, conductor 12, conductor 13, coil |2, conductor 14,and conductor 15 to battery 41. This circuit also supplies current tothe resistor 66 which has one side connected to the junction ofconductors 14 and 15 and has .its other side connected through thevariable contact 1| to the junction of conductors 12 and 13. Energizingcoil |2 closes contacts 6| and 62 so that when the switch 48 is opened acircuit for coil I2 is completed extending from battery In the furtheroperation of the circuit of Fig. 7, when coil I2 is energized contactsprings 6| and 62 are also closed. However, since; switch 46 'forms ashort'circuit around conductor 16 and contact spring 6|, the heater 65receives substantially no current during this phase of the operation.Subsequently, after switch 46 is opened, a circuit for coil I2 isestablished as 'follows: From battery 41 through conductor 46,

coil |2, conductor 56, closed contact springs 36 and 34, conductor 55,conductor 16, conductor 68, heater 65, thermal elements 64 and 63,closed contact springs 62 and 6|, and conductor 56 to battery 41.Accordingly the coil |2 remains energized while at the same time theheater 65 is receiving current and is becoming heated. After theincident time delay interval, the thermally responsive element 64 isdistorted sufliciently to asses tions to delay the operation of contactsprings 26-29 until the time delay occasioned by the thermallyresponsive elements 32 and 13, along with the associated heater 38,permit energizetion of coil l2, and after cbil I2 is energized itremains so until switch 48 is opened. After switch 48 is opened the lefthand portion of the circuit shown in Fig. '7 maintains the coil l2energized, thereby maintaining contacts 26-49 in their operativecondition until the delay occasioned by the thermallv responsiveelements 64 and i3 and the associated heater 65 permit de-energizationof coil i2 and the consequent movement of contacts ZS-29 to theirinoperative positions. The resistor 44 associated with the right handportion of circuit of Fig. 7, and the resistor lil associated with theleft hand portion thereof, may be adjusted to give the desired timedelay interval occasioned by the respective thermally responsiveelements.

Without further elaboration, the foregoing will so fully explain thegist of my invention that others may, by applying current knowledge,readily adapt the same for use under varying conditions of service,without eliminating certain features, which may properly be said toconstitute the essential items of novelty involved, which items areintended to be defined and secured to me by the following claims.

I claim:

1. A time delay relay comprising a coil, contacts adapted to be operatedthereby, closed thermally responsive contacts associated with saidcontacts, an electric heater intimately associated with said thermallyresponsive contacts for controlling the opening thereof after a timedelay, one circuit for energizing said coil, and a circuit in parallelto said one circuit including a normally open pair of said contacts,said thermally responsive contacts and said electric heater, theenergizing of said coil through said one circuit closing said pair ofcontacts thereby energizing said coil and said electric heater throughsaid parallel circuit when said one circuit is opened and thereafteropening said thermally responsive switch to de-energize said coil aftera time delay.

2. A time delay relay comprising a coil, contacts adapted to be operatedthereby, thermally responsive contacts associated with said contacts, anelectric heater intimately associated with said thermally responsivecontacts for controlling the opening thereof after a time delay, timedelay varying means associated with said'electric heater, one circuitfor energizing said coil, and a a normally open pair of said'contacts,said thermally responsive contacts. and said electric heater, theenergizing of said coil through said one circuit closing said pair ofcontacts thereby energizing said coil and saidelectric heater throughsaid parallel circuit when said one circuit is opened and thereafteropen-ingsaid thermally responsive switch to de-energize said coil aftera time delay.

3. A time delay relay comprising a coil, contacts adapted to be operatedthereby, thermally responsive contacts associated with said contacts, anelectric heater intmately associated with said thermally responsivecontacts for controlling the opening thereof after a time delay, aresistor associated with said electric heater for varying the time delayof said thermally responsive means,

,one circuit for energizing said coil, and a circuit in parallel to saidone circuit including a normally open pair of said contacts, saidthermally responsive contacts and said electric heater, the energizingof said coil through said one circuit closing said pair of contactsthereby energizing said coil and said-electric heater through saidparallel circuit when said one circuit is opened and thereafter openingsaid thermally responsive switch to de-energize said coil after a timedelay.

4. A time delay relay comprising a. coil, contacts adapted to beoperated thereby, one energizing circuit for said coil including anormally open pair of said contacts, a second energizing circuit forsaid coil including normally open thermally responsive contacts, a firstelectric heater intimately associated with said thermally responsivecontacts for controlling the closing thereof after a time delay, acircuit for energizing said first electric heater including a normallyclosed pair of said contacts, normally closed thermally responsivecontacts, a second electric heater intimately associated with saidnormally closed thermally responsive contacts, a third circuit forenergizing said coil including said normally closed thermally responsivecontacts, said second heater and a normally open pair of said contacts,and a switch associated with said circuits, whereby first closing saidswitch energizes said first heater through the energizing circuit forsaid first heater to effect energization of said coil after a timedelay, thereby closing said pairs of normally open contacts andenergizing said coil through said one circuit and opening said normallyclosed pair of contacts to de-energize said first heater and thereafteropening said switch energizes said coil through said third circuitthereby to open said normally closed thermally responsive contacts aftera time dela to 1 de-energize said coil.

5. A time delay relay comprising a coil mounted on a frame, a contactpile mounted on said frame, an armature pivotally mounted on said framefor actuation by said coil, said armature including arms engaging thecontacts of said pile for operation of said contacts when said armatureis actuated by said coil, closed thermally responsive contact membersassociated with said contact pile, an electric heater intimatelyassociated with said thermally responsive contact members forcontrolling the opening thereof after a time delay, one circuit forenergizing said coil, and a circuit in parallel to said one circuitincluding a normally open pair of contacts, said thermall res nsivecontact membe circuit in parallel to said one circuit including y m rsand Sam electric heater, the energization of said coll through said onecircuit closing said pair of contacts thereby energizing said coil andsaid electric heater through said parallel circuit when said one circuitis opened and thereafter opening said thermally responsive switch tode-energize said coil after a time delay.

JOHN s. BAKER.

REFERENCES CITED The following references are of record in the file ofthis patent:

v UNITED STATES PATENTS Number Name 7 Date 1,746,827 Fry Feb. 11, 19301,9a3,5oe Willing Dec. 4, 1934 2,057,384 Lamb Oct. 1a, 1930 2,194,634

Betz Mar. 26, 1940

